I have a model with 5 stories of wood on top of a transfer slab with 2 levels of concrete below. The wood portion is laterally supported by wood shear walls and the concrete levels have concrete shear walls. When designing the concrete shear walls below, does ram account for the height at which the applied lateral loads act on the wood levels to increase the global overturning in the system as compared to just applying a lateral load at the transfer slab equal to the sum of the lateral loads on the wood levels above?
Additionally, when I investigate the overturning moments of the concrete shear walls at the base I am finding that the overturning moment (in-plane of the wall) is less than the sum of the applied shear loads multiplied by their respective heights. Why is this?
If all 7 levels are included in the model and the lateral loads are applied at each story, then the overall overturning effect would be included. If the model included the concrete levels only and the lateral load from the wood levels was applied as a lateral load on the transfer level, then that overturning effect would not be included.
You may find the following web page on podium levels helpful:
http://communities.bentley.com/products/structural/structural_analysis___design/w/structural_analysis_and_design__wiki/modeling-podium-slabs
If you have wall groups with intersecting walls forming flanges, a portion of the overturning moment may take the form of axial force couples in the intersecting wall segments. The section "3-Dimensional Effects of Wall Groups" on the web page below has more discussion on this point:
http://communities.bentley.com/products/structural/structural_analysis___design/w/structural_analysis_and_design__wiki/7578.ram-ss-walls-faq